Installation of a solid fuel stove or fireplace insert and connection to a masonry chimney which was designed for open hearth fires requires that a chimney liner be placed within the chimney. This invention relates to a chimney liner system for masonry chimneys.
Most commercially available chimney liner systems call for the insertion of a metal chimney liner in the center of the masonry chimney and the embedment of the metal liner in some kind of cementitous material.
Such prior art systems are expensive to install, are subject to cracking in the event of creosote fires, and very difficult to remove to make repairs. Specifically, when the metal chimney is completely surrounded with solid concrete, in a very hot fire, there is no room for expansion, and the concrete cracks. Upon cooling, the metal liner often buckles inwardly. If a creosote fire then occurs, the flames move around the buckled steel liner, through the cracks in the concrete to the combustible frame of the house. A house fire is inevitable.
Other chimney liner systems disclose straight metal pipe sections for the straight sections and specially made sheet metal sections for offsets in the chimney or for insertion through the damper area. Such liners require specially made factory pipe sections and careful installation.
Still other chimney liner systems consist of a single elongated flexible metal pipe. Since such flexible sections are single wall and transmit heat quite readily, they require some form of outer insulation to meet code requirements. Some flexible chimney lines are embedded in cemetious material as above described, while others are spirally wrapped in a blanket insulation which is contained by a wire web. Such wrapped pipes are subject to tearing of the insulation on the rough inside walls of the masonry chimney.
Another liner system consists of metal pipes with a preformed insulation member snap locked to the outside of the metal pipes as each section of metal pipe is lowered from the top of the chimney. This system is slow to assemble, the insulation may be damaged in transit, and is subject to slippage relative to the metal pipe liner during and after insulation creating rings of uninsulated areas of the metal liner creating "hot spots" which may cause fires due to overheating of combustible material adjacent the "hot spots".